In most of todays modern high speed machines such as compressors, turbines, high speed gears, etc. the axial displacement of the rotating element is highly critical.
Axial displacement of a shaft, for example in a chlorine or Freon compressor which is part of a critical process can indicate a malfunction is occurring either in the process or in the compressor or a related component (gear, turbine, motor).
Some examples of causes that can have an effect on thrust loading or shaft axial shift are: slugs of liquid suddenly sucked into a Freon or chlorine compressor, change of oil supply to the thrust bearing, thermal changes in either the rotating element or the housing of a unit (compressor, turbines, pump, gear, etc.), fluid seal failure changing loading conditions on the rotating element or external thrust transmitted through couplings from driving or driven related machines. Thus, in critical systems indications of a malfunction can be used to sound alarms or even shut the system down before serious damage to the system occurs. To sense shaft displacement, probe type sensors that translate the distance gap to voltage have been used in the past. However, the use of sensors for axial float have always been utilized by insertion of the probe into sensing relationship with the shaft through the back plate of the compressor bearing housing or set into a fixed wall inside the bearing housing. But, because of the development and use of thru drive machines, or if coupling guards or for many other reasons the area of the backplate is not usable for sensor installation, a mounting arrangement for the internal location of the sensor is required. Placement of the sensor within the machine has been accomplished but the arrangement required that the upper half of the bearing housing had to be disassembled at any time adjustment to the sensor had to be made or the sensor replaced.